For Monday, October 23rd, 2023

  1. I’ll post a short video solution to the last daily, but it’s not up yet; I’ll note it here when it is.
  2. Compute the sum of the following two points on this elliptic curve.  $E: y^2 = x^3 + x + 1$ modulo $7$. $ P = (0,1)$ and $Q = (2,2)$.  Compute $P+Q$.
  3. What is $P + \infty$ on this curve?
  4. What is $-P$?
  5. Suppose, on the same curve, we want to compute the sum of $Q$ with itself.  That means we need to find a tangent line!  Compute $Q+Q$.
  6. Show that if $P=(x,0)$ is a point on an elliptic curve, then $2P = \infty$.